Killzone Liberation download pack coming on May 21st?

The website gpstore.co.nz is reporting that a free Killzone Liberation download pack is coming on May 21st. Supposedly, the download pack is going to add extra hours of gameplay, new missions/environments, more enemies, challenge games, vehicles, and boss fights. Also, infrastructure play for all multiplayer maps, new arenas, head to head mode, headset support, and the ability to unlock extra content from the game and Killzone.com. We aren't sure if this is true or not, so we'll just have to wait and see if it actually happens.